HR: 0800h
AN: P11B-0541    [Abstracts]
TI: Probing cometary ice: Finite Difference Time Domain Simulation of Radar Wave Propagation Through Comet Nuclei Dielectric Models
AU: Carley, R A
EM: r.a.carley@sms.ed.ac.uk
AF: Grant Institute of Earth Science, University of Edinburgh, West Mains Road, Edinburgh, EH9 3JW, United Kingdom
AU: * Heggy, E
EM: Heggy@lpi.usra.edu
AF: Lunar and Planetary Institute, 3600 Bay Area Boulevard, Houston, TX 77058, United States
AU: * Heggy, E
EM: Heggy@lpi.usra.edu
AF: Institut de Physique du Globe de Paris, 4 Avenue de Neptune, Saint-Maur des Fosse, 94107, France
AB: The 90 MHz radar-wave experiment, CONSERT (COmet Nucleus Sounding Experiment by Radiowave Transmission), on board the Rosetta mission (ESA, 2004) is expected to probe the nucleus of the comet 67P/Churyumov-Gerasimenko (67P/C-G) to reveal information on its physical properties, chemical composition, and internal structure [Kofman et al., 1998]. This investigation assesses the potential to recognise lithological structure in the comet nucleus with a radar experiment such as CONSERT. Radar simulations at 90 MHz were performed with a Finite Difference Time Domain (FDTD) method. The amplitude and losses of the transmitted and reflected electric field components of an incident radar pulse were evaluated as a function of time. Seven different dielectric models of sections of a hypothetical comet nucleus were used, representative of existing theories of comet nuclei. Values of dielectric constant assigned to these models are based on mixing laws for a porous mixture of ice and meteoritic dust, employing laboratory measured values of relative permittivity for mainly chondritic meteorites. Our results confirm that structural differences such as layers or inclusions are discernable from transmitted and reflected radar signals at 90 MHz, the central frequency of the CONSERT instrument. Such simulations help to constrain the ambiguities that might exist in future radar data associated with the nature of the comet nuclei, whether conglomerate or layered in nature.
DE: 6020 Ices
DE: 6024 Interiors (8147)
DE: 6094 Instruments and techniques
DE: 6210 Comets (6023)
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting